1. Field of the Invention
The present invention relates to an ink jet printer for ejecting ink to print images, such as characters and symbols.
2. Description of the Related Art
Ink jet printers can be divided roughly into two types depending on how they generate force for ejecting ink droplets. Electrothermal conversion types generate force by converting electric power into heat, and electromechanical conversion types generate force by converting electric power into mechanical force.
Electrothermal conversion types use a thermal resistor or other actuator to heat a portion of ink filling an ink chamber to boiling. The force of the resultant expanding vapor bubble ejects an ink droplet through a nozzle of the ink chamber.
Electromechanical conversion types use electric power to mechanically deform piezoelectric material in order to eject ink. That is, a voltage is applied either perpendicular to or parallel with the polarization direction of the piezoelectric material. As a result, the piezoelectric material deforms so as to apply pressure to ink in an ink channel. An ink droplet is ejected from a nozzle of the ink channel as a result.
Electromechanical converting type ink jet printers can be divided into two types. In the first type, a side of an ejection channel is covered by a vibration plate, or a diaphragm. A piezoelectric material is disposed on top of the vibration plate. In the second type, a plurality of ejection channels are cut directly into a plate of piezoelectric material. The ejection channels are partitioned by side walls formed from the piezoelectric material.